AU2020101884A4 - Method for evaluating continental shale gas - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000011156 evaluation Methods 0.000 claims abstract description 41
- 238000004321 preservation Methods 0.000 claims abstract description 28
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 25
- 238000004458 analytical method Methods 0.000 claims abstract description 22
- 238000011161 development Methods 0.000 claims abstract description 18
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 16
- 239000011707 mineral Substances 0.000 claims abstract description 16
- 239000005416 organic matter Substances 0.000 claims abstract description 16
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 230000000704 physical effect Effects 0.000 claims abstract description 10
- 238000003860 storage Methods 0.000 claims abstract description 6
- 239000012530 fluid Substances 0.000 claims description 18
- 238000001179 sorption measurement Methods 0.000 claims description 18
- 230000035699 permeability Effects 0.000 claims description 17
- 239000004576 sand Substances 0.000 claims description 14
- 230000000694 effects Effects 0.000 claims description 8
- 208000013201 Stress fracture Diseases 0.000 claims description 7
- 230000009466 transformation Effects 0.000 claims description 7
- 238000005065 mining Methods 0.000 claims description 6
- 230000009286 beneficial effect Effects 0.000 claims description 3
- 238000004868 gas analysis Methods 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 116
- 238000004519 manufacturing process Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 206010017076 Fracture Diseases 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 208000010392 Bone Fractures Diseases 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000010433 feldspar Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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Abstract
The invention discloses a method for evaluating continental shale gas, which comprises the
following steps: (1) calculating a weighted average value by using the contribution values of
shale thickness, buried depth, organic matter abundance, maturity and area to investigate gas
generation conditions; the weighted average value is calculated by using the contribution
values of shale physical properties and gas content to investigate the reservoir capacity; (2)
when both the gas generation conditions and the reservoir capacity meet the conditions in
step (1), the preservation conditions, exploitability and engineering evaluation are
investigated again; (3) comprehensively evaluating whether the continental shale gas can be
mined according to the gas generation conditions, storage capacity, preservation conditions,
exploitability and engineering evaluation. The method of the invention considers a plurality
of indexes at the same time and provides a technical basis for shale gas exploitation.
-1/1
Method for evaluating continental shale gas
utilizing indexes
Gas Reservoir Preservation Exploitability Engineering
condition capacity conditions evaluation
Mineral
Thickness ofs'hale Shale physical Cap6ek composition Perforation
Buried depth properties analysis P ratio Fracturingfluid
Organic matter
abundance Adsorbedgas Young's modulus Poppant
Maturity Fault
Area Free gas analysis Brittleness index
Formation
pressure
Development
degree of micro
cracks
Fig. 1
Description
-1/1
Method for evaluating continental shale gas utilizing indexes
Gas Reservoir Preservation Exploitability Engineering condition capacity conditions evaluation
Mineral Thickness ofs'hale Shalephysical Cap6ek composition Perforation Buried depth properties analysis P ratio Fracturingfluid Organic matter abundance Adsorbedgas Young's modulus Poppant Maturity Fault Area Free gas analysis Brittleness index Formation pressure
Development degree of micro cracks
Fig. 1
PATENTS ACT 1990
The invention is described in the following statement:-
[0001] The invention relates to a shale gas evaluation method, in particular to a
continental shale gas evaluation method.
[0002] Shale gas refers to unconventional natural gas occurring in the reservoir rock
series dominated by organic-rich shale, which is continuously generated biochemical gas,
thermal gas or their mixture. It can exist in natural fractures and pores in a free state, exist
on the kerogen and clay particles surface in an adsorbed state, and a small amount is
stored in kerogen and asphaltene in a dissolved state. Shale gas is contained in shale
strata, and its formation and enrichment have their own unique characteristics, which is
often distributed in shale hydrocarbon source rock strata with large thickness and wide
distribution in the basin.
[0003] China's continental shale gas is widely distributed and covers a large area. There
are also organic-rich dark mudstones in continental coal measures, which is conducive to
the formation of shale. Especially, the environment of organic-rich dark mudstones as
shale gas reservoir includes Lake Bay, semi deep lake and deep lake. All black
mudstones of Qingshankou Formation of Lower Cretaceous developed in Songliao Basin
in Northeast China, shale of Shanxi Formation in Qinshui Basin in North China, shale of
Upper Member of Shahejie Formation and Lower Member of Shahejie Formation of
Paleogene developed in Bohai Bay Basin, shale of Yanchang Formation of Upper
Triassic developed in Ordos Basin, dark mudstones of Babaoshan Formation of Triassic
in Qaidam Basin in Northwest China and dark mudstones and carbonaceous shale of
Shuixigou Formation developed in Turpan Depression of Tuha Basin are mainly
continental lacustrine deposits.
[0004] With the consumption of coal resources and the increasing emphasis on clean
energy, China will inevitably increase the exploitation and utilization of clean energy
such as natural gas. At present, as a whole, China's shale gas exploration and
development is in the initial stage, and the degree of exploration and development and
research understanding are very low, so it is extremely difficult to correctly evaluate its
resource potential. At present, with reference to relevant foreign standards, the evaluation
index of marine shale gas resources in China has been preliminarily established, but the
index is not systematic and not comprehensive enough.
[0005] Compared with marine shale gas, the thermal evolution of organic matter in
continental shale gas is low, and oil generation (peak) is dominant; continental shale has
high clay mineral content, low diagenesis and poor brittleness. The reservoir space of
continental shale is undeveloped, and the matrix pores are the main ones, while the
organic pores and microfractures are undeveloped and the physical properties are poor;
gas range is small.
[0006] Therefore, the establishment of evaluation method of continental shale gas
resources is helpful to promote the smooth development of shale gas exploration and
development in China.
[0007] The purpose of the present invention is to provide a method for evaluating
continental shale gas, which solves the problem that there is no evaluation method for
continental shale gas in China, can simultaneously consider multiple indexes, and
provides a technical basis for shale gas exploitation.
[0008] In order to achieve the above purpose, the present invention provides a method for
evaluating continental shale gas, which comprises the following steps.
[0009] (1) The weighted average value is calculated by the contribution values of shale
thickness, buried depth, organic matter abundance, maturity, and area to investigate the
gas generation conditions. The weighted average value is calculated by using the
contribution values of shale physical properties and gas content to investigate the
reservoir capacity.
[0010] For the gas generation conditions, the shale thickness is over 30m, the buried
depth is under 3500m, the abundance of organic matter is 1-4%, the maturity is over
1.5%, and the area is over 50km2.
[0011] Wherein, for the reservoir capacity, the shale physical properties are investigated
by porosity and permeability, and the porosity is above 5% and the permeability is above
x10-3 [m2; the gas content is investigated by adsorption gas and free gas, and the total
volume of adsorption gas and free gas is above 2m3/t, and the ratio of free gas to
adsorption gas is above 0.1;
[0012] (2) When both the gas generation conditions and the reservoir capacity meet the
conditions in step (1), the preservation conditions, exploitability and engineering evaluation are investigated again; when the gas generation condition or reservoir capacity does not meet the conditions in step (1), there is no mining condition.
[0013] Among them, for the preservation conditions, the weighted average value is
calculated by using the contribution values of caprock analysis and fault analysis to
investigate the preservation conditions.
[0014] Among them, for the exploitability, the weighted average value is calculated by
using the contribution values of mineral composition, Poisson's ratio, Young's modulus,
brittleness index, formation pressure coefficient, horizontal stress difference and micro
fracture development degree to investigate the exploitability. The mineral component
content is 30-50%, the Poisson's ratio is below 0.4%, the Young's modulus content is 20
Gpa, the brittleness index is above 30%, the formation pressure coefficient is above
1.0, the horizontal stress difference is below 15Mpa, and the micro-cracks development
degree is developing.
[0015] Among them, for the engineering evaluation, the weighted average value is
calculated by using perforation, fracturing fluid, sand carrying ratio and proppant
contribution values to investigate the engineering evaluation. The backflow amount of the
fracturing fluid is 10-30%, the sand carrying ratio is less than 5%, and the proppant
consumption is medium.
[0016] (3) Comprehensively evaluate whether the continental shale gas can be mined
according to the gas generation conditions, storage capacity, preservation conditions,
exploitability, and engineering evaluation.
[0017] The weighted weights of gas generation condition, reservoir capacity and easy
exploitation are all greater than 1, and the weighted average value is calculated for the contribution value of gas generation condition, reservoir capacity, preservation condition, easy exploitation and engineering evaluation. When the weighted average value is greater than 1, the continental shale gas can be exploited.
[0018] Preferably, the contribution values of the gas generation condition, reservoir
capacity, preservation condition, exploitability and engineering evaluation are 25%, 25%,
%, 20% and 15% respectively.
[0019] Preferably, for the gas generation conditions, the contribution values of shale
thickness, buried depth, organic matter abundance, maturity and area are 15%, 20%,
%, 30% and 10% in turn.
[0020] Preferably, for the reservoir capacity, the contribution values of porosity,
permeability, total volume of adsorbed gas and free gas and free gas/adsorbed gas ratio
are 20%, 20%, 10% and 30% in turn.
[0021] Preferably, for the preservation conditions, the contribution values of the caprock
analysis and fault analysis are 60% and 40%, respectively. According to the caprock
analysis, the transformation degree of caprock is judged, and the fault structure activity is
judged according to the fault analysis. If the transformation degree of caprock and the
fault structure activity are moderate or weak, it is beneficial to exploit.
[0022] Preferably, for the exploitability, the contribution values of mineral composition,
Poisson's ratio, Young's modulus, brittleness index, formation pressure coefficient,
horizontal stress difference and micro-fracture development degree are 20%, 10%, 10%,
2 0% , 10%, 15% and 15% respectively.
[0023] Preferably, for the engineering evaluation, the contribution values of perforation,
fracturing fluid, sand carrying ratio and proppant are 25%, 25%, 30% and 20% in turn.
[0024] Preferably, for the gas generation condition, the shale thickness is above 50m, the
buried depth is below 2000m, the organic matter abundance is 24%, the maturity is
above 2%, and the area is above 1OOkm2; as for the reservoir capacity, the shale physical
properties are investigated by porosity and permeability, and the porosity is above 10%
and the permeability is above 100x10-3 [m2. The gas content is investigated by
adsorption gas and free gas. The total volume of adsorption gas and free gas is above
4m3/t, and the ratio of free gas to adsorption gas is above 0.3.
[0025] Preferably, for the exploitability, the mineral component content is 4 0 - 5 0 %, the
Poisson's ratio is below 0.3%, the Young's modulus content is 30-40 Gpa, the brittleness
index is above 50%, the formation pressure coefficient is above 1.3, the horizontal stress
difference is below 1OMpa, and the micro-cracks are developed.
[0026] Preferably, for the engineering evaluation, the backflow amount of the fracturing
fluid is 3 0 - 1 0 %, the sand carrying ratio is less than 5%, and the proppant consumption is
less.
[0027] The method for evaluating continental shale gas solves the problem that there is
no evaluation method for continental shale gas in China, and has the following
advantages.
[0028] The method comprehensively considers the influence of various factors on
continental shale gas. Gas generation condition is the core, gas storage capacity is the
foundation, preservation condition is the foundation, fracturing is the key, and
engineering evaluation is the guarantee. Considering the strong tectonic activity of
continental shale gas in China, the continental shale gas has been reformed to varying degrees, and combined with engineering evaluation, the assessment index is comprehensive, which provides a basis for the exploitation of continental shale gas.
[0029] Fig. 1 is a schematic diagram of the method for evaluating continental shale gas
according to the present invention.
[0030] The technical scheme in the embodiments of the present invention will be
described clearly and completely below. Obviously, the described embodiments are only
part of the embodiments of the present invention, not all of them. Based on the
embodiments of the present invention, all other embodiments obtained by ordinary
technicians in the field without creative labor belong to the scope of protection of the
present invention.
[0031] A method for evaluating continental shale gas, as shown in fig. 1 which is a
schematic diagram of it, comprises the following steps.
[0032] (1) The weighted average value is calculated by the contribution values of shale
thickness, buried depth, organic matter abundance, maturity, and area to investigate the
gas generation conditions. The weighted average value is calculated by using the
contribution values of shale physical properties and gas content to investigate the
reservoir capacity.
[0033] For the gas generation conditions, the shale thickness is over 30m, the buried
depth is under 3500m, the abundance of organic matter is 14%, the maturity is over
1.5%, and the area is over 50km2.
[0034] Wherein, for the reservoir capacity, the shale physical properties are investigated
by porosity and permeability, and the porosity is above 5% and the permeability is above
x10-3 [m2; the gas content is investigated by adsorption gas and free gas, and the total
volume of adsorption gas and free gas is above 2m3/t, and the ratio of free gas to
adsorption gas is above 0.1;
[0035] (2) When both the gas generation conditions and the reservoir capacity meet the
conditions in step (1), the preservation conditions, exploitability and engineering
evaluation are investigated again; when the gas generation condition or reservoir capacity
does not meet the conditions in step (1), there is no mining condition.
[0036] Among them, for the preservation conditions, the weighted average value is
calculated by using the contribution values of caprock analysis and fault analysis to
investigate the preservation conditions.
[0037] Among them, for the exploitability, the weighted average value is calculated by
using the contribution values of mineral composition, Poisson's ratio, Young's modulus,
brittleness index, formation pressure coefficient, horizontal stress difference and micro
fracture development degree to investigate the exploitability. The mineral component
content is 30-50%, the Poisson's ratio is below 0.4%, the Young's modulus content is 20
Gpa, the brittleness index is above 30%, the formation pressure coefficient is above
1.0, the horizontal stress difference is below 15Mpa, and the micro-cracks development
degree is developing.
[0038] Among them, for the engineering evaluation, the weighted average value is
calculated by using perforation, fracturing fluid, sand carrying ratio and proppant
contribution values to investigate the engineering evaluation. The backflow amount of the fracturing fluid is 10-30%, the sand carrying ratio is less than 5%, and the proppant consumption is medium.
[0039] (3) Comprehensively evaluate whether the continental shale gas can be mined
according to the gas generation conditions, storage capacity, preservation conditions,
exploitability, and engineering evaluation.
[0040] The weighted weights of gas generation condition, reservoir capacity and easy
exploitation are all greater than 1, and the weighted average value is calculated for the
contribution value of gas generation condition, reservoir capacity, preservation condition,
easy exploitation and engineering evaluation. When the weighted average value is greater
than 1, the continental shale gas can be exploited.
[0041] According to an embodiment of the present invention, the contribution values of
gas generation conditions, reservoir capacity, preservation conditions, exploitability and
engineering evaluation are 25%, 25%, 10%, 20% and 15% in turn.
[0042] According to an embodiment of the present invention, for gas generation
conditions, the contribution values of shale thickness, buried depth, organic matter
abundance, maturity and area are 15%, 20%, 25%, 30% and 10% in turn.
[0043] According to an embodiment of the present invention, for the reservoir capacity,
the contribution values of porosity, permeability, total volume of adsorbed gas and free
gas and free gas/adsorbed gas ratio are 20%, 20%, 10% and 30% in turn.
[0044] According to an embodiment of the present invention, for the preservation
conditions, the contribution values of the caprock analysis and fault analysis are 60% and
%, respectively. According to the caprock analysis, the transformation degree of
caprock is judged, and the fault structure activity is judged according to the fault analysis.
If the transformation degree of caprock and the fault structure activity are moderate or
weak, it is beneficial to exploit.
[0045] According to an embodiment of the present invention, for the exploitability, the
contribution values of mineral composition, Poisson's ratio, Young's modulus, brittleness
index, formation pressure coefficient, horizontal stress difference and micro-fracture
development degree are 20%, 10%, 10%, 20%, 10%, 15% and 15% respectively.
[0046] According to an embodiment of the present invention, for the engineering
evaluation, the contribution values of perforation, fracturing fluid, sand carrying ratio and
proppant are 25%, 25%, 30% and 20% in turn.
[0047] According to an embodiment of the present invention, for the gas generation
condition, the shale thickness is above 50m, the buried depth is below 2000m, the organic
matter abundance is 24%, the maturity is above 2%, and the area is above1OOkm2; as
for the reservoir capacity, the shale physical properties are investigated by porosity and
permeability, and the porosity is above 10% and the permeability is above 100x10-3[m2.
The gas content is investigated by adsorption gas and free gas. The total volume of
adsorption gas and free gas is above 4m3/t, and the ratio of free gas to adsorption gas is
above 0.3.
[0048] According to an embodiment of the present invention, for the exploitability, the
mineral component content is 40-50%, the Poisson's ratio is below 0.3%, the Young's
modulus content is 30-40 Gpa, the brittleness index is above 50%, the formation pressure
coefficient is above 1.3, the horizontal stress difference is below 1OMpa, and the micro
cracks are developed.
[0049] According to an embodiment of the present invention, for engineering evaluation,
the amount of fracturing fluid flowing back is less, the sand carrying ratio is less than 5%,
and the proppant consumption is less.
[0050] Each index of reservoir capacity, i.e. porosity, permeability, total volume of
adsorbed gas and free gas, and ratio of free gas to adsorbed gas, must reach the above
range, otherwise, fracturing and gas production will be affected. Gas generation condition
is the core, so its weighted weight is required to be greater than 1, and exploitability is the
key to investigate fracturing. If it can't be pressed out, it can't be p exploited, so its
weighted weight is required to be greater than 1.
Table 1: Evaluation Index Table of Continental Shale Gas
Judgment
Evaluation index Weight Basic indicators
% Low Medium High
Thickness of shale (m) 15 30 30-50 >50
Buried depth (m) 20 >3500 2000-3500 500-2000 Gas condition Organic matter abundance (TOC)% 25 <1 1-2 2-4
Maturity (Ro)% 30 <1.5 1.5-2 >2
Area (km 2) 10 <50 50-100 >100
20 2-5 5-10 >10 Shale physical Porosity% properties permeability 10- 20 0-10 10-100 >100 Reservoir 3Pm2 capacity Adsorbed gas+ >1 2-4 >4 Gas content free gas (m 3/t) 10
Gas structure: free 30 <0.1 0.1-0.3 >0.3 gas/adsorbed gas
Preservation Caprock analysis 60 Strong Medium Weak
conditions Fault analysis 40 Strong Medium Weak
Quartz + Feldspar Mineral 20 composition 30< 30-40 40-50
Poisson's ratio% 10 >0.4 0.3-0.4 <0.3 Exploitability
Young's modulus 10 <20 20-30 30-40 (Gpa)
Brittleness index% 20 <30 30-50 >50
Formation pressure 10 <1 1.0-1.3 >1.3 coefficient
Horizontal stress 15 >15 10-15 <10 difference (Mpa)
Development degree of micro- 15 Do not develop General Development cracks
Difficult to
25 select Controlled by Not controlled by perforation perforation horizon horizon position
The formula is The formula is The formula is Engineering evaluation 25 complex, and the simple, and the simple, and the Fracturing fluid backflow fluid is backflow backflow amount more than 50% amount is 30-10%
Sand carrying 30 >10 5-10 <5 ratio%
proppant 20 many medium Less
[0051] In Table 1, gas generation conditions and reservoir capacity have relevant
specifications. The higher the index, the better the exploitability. The conditions of
caprock are qualitative and roughly judged. The weaker the transformation is, the weaker
the tectonic activity is, and the more favourable it is for gas preservation and exploitation.
Exploitability and engineering evaluation are the main indexes of exploitability
evaluation, which are summarized through actual mining tests. Different shale gas mining
areas have different index data. Generally speaking, the higher the brittle mineral content,
the higher the brittleness index, the larger Young's modulus and formation pressure
coefficient, while the smaller Poisson's ratio and horizontal stress difference, the more
favourable it is for the exploitability. The more developed the micro fractures, the more
gas structure can be changed, and the more free gas is, the more favourable it is for exploitation. The perforation position is not controlled by lithology and the simpler the fracturing fluid formula is, which belongs to low-grade fracturing fluid. The less proppant is used, the lower the sand carrying ratio, and the more economical it is to meet the gas production requirements. According to the data comparison of known mining areas, the more backflow fluid, the lower gas production, and the less backflow fluid, the higher gas production.
[0052] To sum up, the method for evaluating continental shale gas of the present
invention can consider multiple indexes at the same time and provides a technical basis
for shale gas exploitation.
[0053] Although the content of the present invention has been described in detail by the
above preferred embodiments, it should be recognized that the above description should
not be regarded as limiting the present invention. Many modifications and alternatives to
the present invention will be apparent to those skilled in the art after reading the above.
Therefore, the scope of protection of the present invention should be defined by the
appended claims.
Claims (10)
1. A method for evaluating continental shale gas comprising the following steps.
(1) A weighted average value is calculated by the contribution values of shale thickness,
buried depth, organic matter abundance maturity and area to investigate the gas
generation conditions, wherein the weighted average value is calculated by using the
contribution values of shale physical properties and gas content to investigate the
reservoir capacity;
wherein, for the gas generation conditions, the shale thickness is over 30m, the buried
depth is under 3500m, the abundance of organic matter is 1 4 %, the maturity is over
1.5%, and the area is over 50km2 ;
wherein, for the reservoir capacity, the shale physical properties are investigated by
porosity and permeability, and the porosity is above 5% and the permeability is above
lOx10 3 jm2 ; the gas content is investigated by adsorption gas and free gas, and the total
volume of adsorption gas and free gas is above 2m3/t, and the ratio of free gas to
adsorption gas is above 0.1;
(2) when both the gas generation conditions and the reservoir capacity meet the
conditions in step (1), the preservation conditions, exploitability and engineering
evaluation are investigated; when the gas generation condition or reservoir capacity does
not meet the conditions in step (1), there is no mining condition; for the preservation conditions, the weighted average value is calculated by using the contribution values of caprock analysis and fault analysis to investigate the preservation conditions; for the exploitability, the weighted average value is calculated by using the contribution values of mineral composition, Poisson's ratio, Young's modulus, brittleness index, formation pressure coefficient, horizontal stress difference and micro-fracture development degree to investigate the exploitability; the mineral component content is
-50%, the Poisson's ratio is below 0.4%, the Young's modulus content is 20-40 Gpa,
the brittleness index is above 30%, the formation pressure coefficient is above 1.0, the
horizontal stress difference is below 15Mpa and the micro-fracture development degree is
general;
among them, for the engineering evaluation, the weighted average value is calculated by
using perforation, fracturing fluid, sand carrying ratio and proppant contribution values to
investigate the engineering evaluation; the flow-back amount of the fracturing fluid is
between 30% and 50%, the sand carrying ratio is less than 4%, and the amount of
proppant is medium;
(3) Comprehensively evaluate whether the continental shale gas can be mined according
to the gas generation conditions, storage capacity, preservation conditions exploitability
and engineering evaluation;
wherein the weighted weights of gas generation condition, reservoir capacity and
exploitability are all greater than 1, and the weighted average value is calculated for the contribution of gas generation condition, reservoir capacity, preservation condition, exploitability, and engineering evaluation; when the weighted average value is greater than 1, the continental shale gas can be exploited.
2. The method for evaluating continental shale gas according to claim 1 wherein the
contribution values of gas generation conditions, storage capacity, preservation
conditions, exploitability and engineering evaluation are 25%, 25%, 10%, 20% and 15%
in turn.
3. The method for evaluating continental shale gas according to claim 1 wherein for the
gas generation conditions, the contribution values of shale thickness, buried depth,
organic matter abundance, maturity and area are 15%, 20%, 25%, 30% and 10%
respectively.
4. The method for evaluating continental shale gas according to claim 1 wherein for the
reservoir capacity, the contribution values of porosity, permeability, total volume of
adsorbed gas and free gas and free gas/adsorbed gas ratio are 20%, 20%, 10% and 30%
respectively.
5. The method for evaluating continental shale gas according to claim 1 wherein, for the
preservation conditions, the contribution values of the caprock analysis and fault analysis
are 60% and 40%, respectively; judge the caprock transformation degree according to the
caprock analysis and judge the fault structure activity according to the fault analysis; if
the transformation degrees of caprock and the fault structure activity are moderate or
weak, it is beneficial to mine.
6. The method for evaluating continental shale gas according to claim 1 wherein, for
exploitability, the contribution values of mineral composition, Poisson's ratio, Young's
modulus, brittleness index, formation pressure coefficient, horizontal stress difference
and micro-fracture development degree are 20%, 10%, 10%, 20%, 10%, 15% and 15%
respectively.
7. The method for evaluating continental shale gas according to claim 1 wherein, for the
engineering evaluation, the contribution values of perforation, fracturing fluid, sand
carrying ratio and proppant are 25%, 25%, 30% and 20% in turn.
8. The method for evaluating continental shale gas according to claim 1 wherein, for the
gas generation condition, the shale thickness is more than 50m, the buried depth is under
2000m, the organic matter abundance is 24%, the maturity is more than 2%, and the area
is more than 100km 2;
wherein, for the reservoir capacity, the shale physical properties are investigated by
porosity and permeability, and the porosity is above 10% and the permeability is above
100X10-3 jm2 ; the gas content is investigated by adsorption gas and free gas; the total
volume of adsorption gas and free gas is above 4m3/t, and the ratio of free gas to
adsorption gas is above 0.3.
9. The method for evaluating continental shale gas according to claim 1 wherein the
content of mineral components is 40-50%, the Poisson's ratio is below 0. 3 %, the Young's
modulus content is 30-40 Gpa, the brittleness index is above 50%, the formation pressure coefficient is above 1.3, the horizontal stress difference is below 1OMpa, and the micro cracks development degree is developing.
10. The method for evaluating continental shale gas according to claim 1 wherein, for the
engineering evaluation, the backflow amount of the fracturing fluid is small which is
between 40% and 30%; the sand carrying ratio is less than 4%, and the proppant
consumption is less.
-1/1-
Fig. 1
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112360444A (en) * | 2020-10-16 | 2021-02-12 | 中国石油天然气股份有限公司 | Method and device for quantitative sorting processing of trap targets |
| CN112392448A (en) * | 2020-11-24 | 2021-02-23 | 中国石油天然气股份有限公司 | Multilayer dense sandstone gas reservoir perforation well section optimization method |
| CN112878987A (en) * | 2021-01-25 | 2021-06-01 | 长江大学 | Method for calculating shale gas well control reserves by using production data |
| CN117408434A (en) * | 2023-11-17 | 2024-01-16 | 成都理工大学 | Shale gas resource amount prediction method and device |
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2020
- 2020-08-19 AU AU2020101884A patent/AU2020101884A4/en not_active Ceased
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112360444A (en) * | 2020-10-16 | 2021-02-12 | 中国石油天然气股份有限公司 | Method and device for quantitative sorting processing of trap targets |
| CN112360444B (en) * | 2020-10-16 | 2023-08-22 | 中国石油天然气股份有限公司 | Quantitative sorting processing method and device for trap targets |
| CN112392448A (en) * | 2020-11-24 | 2021-02-23 | 中国石油天然气股份有限公司 | Multilayer dense sandstone gas reservoir perforation well section optimization method |
| CN112392448B (en) * | 2020-11-24 | 2023-05-26 | 中国石油天然气股份有限公司 | Multi-layer system compact sandstone gas reservoir perforation well section optimization method |
| CN112878987A (en) * | 2021-01-25 | 2021-06-01 | 长江大学 | Method for calculating shale gas well control reserves by using production data |
| CN112878987B (en) * | 2021-01-25 | 2024-01-19 | 长江大学 | Method for calculating shale gas well control reserves by using production data |
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